Microsoft has launched the preview edition of its next consumer operating system (OS), Windows 8.

From today users of Windows 7 will be able totry out the “reimagined” software ahead of its full release. The company calls it the most significant redesign of the Windows interface since its groundbreaking Windows 95 OS. The system’s design draws heavily on the “Metro” interface utilised on the current Windows Phone platform. The Windows 8 developer preview launched late last year and has been downloaded more than three million times.

Windows president Steven Sinofsky said more than 100,000 changes had been made since the developer version went public. For the first time since its inception, the trademark Windows “Start” button will no longer appear – instead being replaced by a sliding panel-based menu.

The OS is Microsoft’s attempt at combining a shared look and feel for smartphones, tablets and desktop computers – mirroring similar approaches from key competitors Apple and Google. The slide interface is paired with a more traditional-looking Windows layout to allow familiar use of programs such as Excel and Word.

“Windows 8 is a generational change in the Windows operating system,” said Mr Sinofsky at the launch event, held at Mobile World Congress in Barcelona. “Apps bring to life the operating system. The more apps you have, the better your experience.” A release date for the finished version of Windows 8 has not yet been announced.